Barium titanate foam ceramics loaded with micro/nano silver and preparation method thereof

Abstract

Disclosed are a micrometer/nanometer silver-loaded barium titanate foam ceramic and a preparation method therefor. An organic additive is used as an auxiliary; deionized water is used as a solvent; nanometer barium titanate is used as a ceramic raw material; and same are mixed and ground so as to form a slurry. A pre-treated polymer sponge is impregnated in the slurry for slurry coating treatment and a barium titanate foam ceramic blank is obtained after drying; and then a barium titanate foam ceramic is obtained through sintering. Through dopamine modification, micrometer/nanometer silver is in-situ deposited on a skeleton surface so as to obtain a modified micrometer/nanometer silver-loaded barium titanate foam ceramic. The modified micrometer/nanometer silver-loaded barium titanate foam ceramic is then put into a newly prepared Tollens' reagent for further reduction so as to obtain a micrometer/nanometer silver-loaded barium titanate foam ceramic with a three-dimensional network skeleton structure.

What we claim: 
     
       1. A preparation method of barium titanate foam ceramics loaded with micro/nano silver, wherein comprising the following steps:
 (1) by weight, 100 parts of nano barium titanate and 30 to 120 parts of an aqueous solution of organic binder with a concentration of 1 to 15 wt % are sufficiently ground to obtain a slurry A; 10 to 80 parts of an aqueous solution of organic rheological agent with a concentration of 0.5 to 3 wt % are added into the slurry A to form a first mixture, and the first mixture is sufficiently ground to obtain a slurry B; 20 to 80 parts of an aqueous solution of organic dispersant with a concentration of 0.5 to 3 wt % are added into the slurry B to form a second mixture, and the second mixture is sufficiently ground to obtain a slurry C; 
 (2) a polymer sponge having a specification of 15 to 35 PPI is soaked in an aqueous solution of sodium hydroxide with a concentration of 5 to 20 wt %, after heated up to 50 to 75° C. and kept at that temperature for 2 to 6 h, the polymer sponge is taken out and washed with deionized water, following by drying to obtain a polymer sponge D; at room temperature, the polymer sponge D is soaked in an aqueous surfactant solution with a concentration of 0.5 to 3 wt % for 2 to 6 h, then took out and removed the excess surfactant, after dried at 40 to 80° C., a pretreated polymer sponge E is obtained; 
 (3) the pretreated polymer sponge E is soaked in the slurry C prepared in step (1), and maintained for 1 to 10 min at room temperature, an excess slurry in the sponge is removed by extrusion, and the sponge is dried at 40 to 80° C.; repeating processes of removing the excess slurry and drying for 1 to 7 times, a green body of foam ceramics based on barium titanate is obtained; 
 (4) the green body of barium titanate foam ceramics prepared in step (3) is heated from room temperature to 100-300° C. at a rate of 0.5-5° C./min, and then raised to 500-700° C. at a rate of 0.5-5° C./min and maintained at that temperature for 0.5-2 h, after that, continuously heated to 1000-1500° C. at a rate of 2-10° C./min and kept at that temperature for 1-5 h, after the furnace is cooled to room temperature, barium titanate foam ceramics are obtained; 
 (5) using buffering agent or buffer, water and dopamine hydrochloride to prepare dopamine aqueous solution with a concentration of 0.5-10 g/L; of which pH value is adjusted to 8.3-8.8 with alkali to obtain solution F; barium titanate foam ceramics prepared in step (4) are soaked in solution F and kept at room temperature for 1 to 24 h, followed by washing with deionized water and drying successively, to obtain dopamine-modified barium titanate foam ceramics; 
 (6) by volume, 4 to 20 parts of stabilizer aqueous solution with a concentration of 0.1-1 wt % are added into 100 parts of a fresh ammoniacal silver solution with a concentration of 0.03-0.3 mol/L to form a third mixture, the third mixture is uniformly mixed to obtain solution G; the dopamine-modified barium titanate foam ceramics prepared in step (5) are soaked in solution G and kept at room temperature for 0.5-24 h to obtain barium titanate foam ceramics loaded with nano silver, into which 50-300 parts of reducing agent aqueous solution having a concentration of 1-30 g/L are added and kept at room temperature for 0.1-5 h, followed by washing with deionized water and drying successively, to obtain barium titanate foam ceramics loaded with micro/nano silver. 
 
     
     
       2. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said polymer sponge includes a polymer material selected from the group consisting of polyurethane, polystyrene, and polyvinyl chloride. 
     
     
       3. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said nano barium titanate has an average diameter of less than or equal to 100 nm. 
     
     
       4. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said organic binder is one or more selected from the group consisting of polyvinyl alcohol, carboxymethyl cellulose and methyl cellulose; said organic rheological agent is one or more selected from the group consisting of carboxymethyl cellulose and hydroxyhexyl cellulose; said organic dispersant is one or more selected from the group consisting of polyacrylamide, polyethyleneimine and polyacrylic acid amine. 
     
     
       5. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said surfactant is one or more selected from the group consisting of carboxymethyl cellulose and polyethyleneimine. 
     
     
       6. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said stabilizer is one or more selected from the group consisting of polyvinylpyrrolidone and sodium alginate. 
     
     
       7. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said reducing agent is one or more selected from the group consisting of hydrazine hydrate, sodium citrate, sodium borohydride, glucose and ascorbic acid. 
     
     
       8. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said buffering agent or buffer is selected from the group consisting of Tris-HCl, disodium hydrogen phosphate, and sodium dihydrogen phosphate buffer. 
     
     
       9. The preparation method of barium titanate foam ceramics loaded with micro/nano silver according to  claim 1 , wherein said alkali is selected from the group consisting of sodium hydroxide and aqueous ammonia solution. 
     
     
       10. Barium titanate foam ceramics loaded with micro/nano silver prepared through the preparation method according to  claim 1 .